Chapter 3: Orthos, Exploded Views & Callout Sheets

Created by Sarah Choi (prompt writer using ChatGPT)

Orthos, Exploded Views & Callout Sheets for Weapon Concept Artists

From brief → ideation → iteration → finals → handoff. Written equally for concept‑phase artists and production‑minded artists.

Why this trio matters

The “finals” most likely to be read by downstream teams are not your beauty renders—they’re the orthographics, exploded views, and callout sheets. These documents are where silhouette intention becomes buildable truth: dimensions, datum references, action paths, attachment envelopes, and material logic. When done well, they shorten modeling cycles, reduce rigging guesswork, and prevent costly retrofits late in production. When rushed, they create ambiguity that is expensive to fix in engine.

Orthos establish the what (shape at scale); exploded views establish the how (assembly and service logic); callout sheets establish the why (design rationale, constraints, and handoff instructions). Treat them as a coherent package, not three unrelated artifacts.

Orthographics: the contract for form and scale

Purpose. Communicate the final exterior shape with unambiguous proportions and consistent, world‑scale dimensioning across views.

Minimum view set. Side (primary), top, bottom, front, rear. For bullpups or asymmetrical receivers, include the opposite side or a partial inset of unique features.

Scale & units. Always show a 100 mm and 1 in scale bar. Use millimeters as master units; include imperial conversions if the studio requests them. Annotate world scale (e.g., 1.0 = 1 m in engine) in the title block.

Datums & centerlines. Define:

  • Primary datum: centerline along bore axis (Z‑axis).
  • Secondary: receiver mid‑plane (Y‑axis).
  • Tertiary: top rail reference (X‑axis origin at rear face). Show these on every view. All dimensions should reference a datum—not floating edges.

Dimensioning strategy. Dimension criticals, not everything: overall length (OAL), barrel visual length, receiver block length/height/depth, stock extension range, optic rail length and height over bore, magazine projection depth, muzzle thread outer diameter, hand‑clearance windows, and sling anchor positions. Use chain dimensions sparingly; prefer baseline dimensions from datums so errors don’t stack.

Line discipline.

  • Visible edges: heavy line weight.
  • Hidden geometry (e.g., internal bolt travel): dashed, light.
  • Section cuts: long‑dash + dot pattern, labeled with arrows and section letters (A‑A, B‑B).
  • Callout leaders: 45° or 30° lines, consistent arrowheads.

Silhouette integrity checks. Include a small corner swatch with the silhouette at icon size (48 px, 96 px) to ensure class readability survives the final proportion adjustments.

Material blocking. Use a neutral value map (3–4 swatches) to indicate material domains (metal receiver, polymer handguard, rubber butt pad, glass optic). Avoid texture—these are maps for modeling breakups and texel sets.

Orthographic extras (when needed).

  • Section views through the action to show bolt path or battery bay.
  • Alternate states: stock collapsed/extended, charging handle locked forward vs pulled, safety positions.
  • Variant overlays: thin ghost lines to compare A/B deltas if the team hasn’t fully locked.

Exploded views: assembly logic and serviceability

Purpose. Show how parts stack, index, and fasten. Convey both build order and maintenance access. This prevents non‑manifold nightmares for modeling and gives rigging/FX clear anchor points.

Explode philosophy. Explode along natural axes and fastener directions. Maintain believable spacing (10–30 mm gaps) unless large assemblies require more. Keep components on rails; avoid chaotic starbursts.

Bill of Materials (BOM). Number each unique part (01, 02, 03…). Provide a table with: part name, material class, finish, texture set ID, estimated tris budget, rigging note (bone? yes/no), animation relevance (e.g., reciprocates, rotates, springs), and damage state potential (detach, deform, scorch only).

Sub‑assemblies first. Group logical modules: Receiver core, Barrel & muzzle stack, Grip & trigger pack, Magazine & feed, Stock/buffer, Charging system, Optic & rail. Explode each sub‑assembly minimally, then show a second plate with the sub‑assemblies separating from the core.

Fastening ideology. Indicate how modules secure: dovetail + captive screws, hinge + latch, bayonet twist‑lock, captive pins. Use small icons or standardized symbols for screw types and directions.

Motion arrows & clearances. Use distinct arrows: solid for assembly direction, hollow for operational motion (e.g., bolt travel, cylinder swing). Add clearance boxes where motion requires space, labeled with min gaps.

Tolerance & alignment. For parts that must align tightly (optic rail to receiver, suppressor to shoulder), add a tolerance note (e.g., ±0.5 mm visual alignment), even if it’s only visual—this communicates polish priorities to modeling and QA.

Exploded‑view readability. Keep line weights lighter than orthos to reduce visual noise. Fade background parts with 70–80% opacity while the focused sub‑assembly is at 100%.

Callout sheets: decisions and constraints in plain view

Purpose. Translate intent into actionable notes for modeling, rigging, animation, VFX, audio, and gameplay. Callouts should answer “what is sacred vs flexible?” and “where will this part move, collide, or emit?”

Core callout categories.

1) Animation & rigging. Hand placements (primary/secondary grips), charge arc, reload choreo beats (mag drop path, cylinder swing angle, cell swap plane), safety/selector reach zones, sling anchor planes, stock extension range. Include a small contact‑sheet of the four core actions (charge, fire stance, reload hero beat, inspect) with ghosted frames.

2) Attachment & envelope. Optic eye line height, rail lengths, muzzle device threads and max OD, under‑barrel hardpoint type and bounding box, side saddle/laser footprints, cable routing lanes (if present). Clearly show do‑not‑occupy volumes.

3) Mechanical plausibility. Ejection port ideology (side/top/bottom), bolt travel distance, gas/vent paths, heat shielding zones, battery bay access. Add red No‑Go hatching over surfaces that must not be gripped during firing (heat, reciprocation).

4) Material & finish. PBR targets per domain (metal roughness range, polymer sheen, rubber softness cue), edge wear policy (hero edges vs protected edges), decal lanes reserved for skins. State texel density targets per texture set (e.g., 512 px/10 cm for attachments, 1024 px/10 cm for hero receiver).

5) LOD & proxy. Sacred planes/curves for LOD1/2, silhouette vows (front signature, top line, grip cluster), collision proxy guidance (magazine, muzzle, optic). If gameplay relies on precise hit proxies (e.g., suppressor hitbox), note it explicitly.

6) Governance & naming. Stable asset ID, matrix row reference, variant suffix logic, version number, and links to related silhouettes/proportion sheets. Include “retired” notes if replacing a legacy model.

Callout tone. Be decisive, not tentative. Use verbs (“Reserve,” “Avoid,” “Mount”) and keep each callout under ~20 words. Prioritize issues that change geometry or rig.

Cross‑team clarity: what each discipline needs to see

Modeling. Datums, critical dimensions, part splits that follow material boundaries, fastening ideology, and texel/trim intentions. Clear evidence of non‑interpenetration when animated.

Rigging & Animation. Bone list with expected constraints (e.g., bolt linear, charging handle linked, stock telescoping), motion ranges, and overlap avoidance. Reload hero beat visibility in silhouette.

VFX & Audio. Muzzle gas vents, ejection path, moving seals, heat sink surfaces, contact surfaces for foley (metal on metal, polymer on sling rings), and any special effect emitters (charge coils, plasma vents).

Gameplay/Design. Attachment compatibility matrix, ejection side (for handedness), ADS line, magazine type/capacity hints, and any collision concerns in first person.

QA & Tech Art. World scale, naming conventions, LOD vows, and test cases (attachments that push worst‑case collisions).

Visual language & layout hygiene

  • Title block with asset ID, class, faction, scale, date, version, author, and status (Concept Final, Ready for Modeling, Post‑Model Paintover).
  • Grid and gutters. Use a consistent grid (e.g., 8 pt) and 12–16 mm gutters; align views and tables. White space is information.
  • Contrast discipline. Avoid heavy noise textures; use flat values and reserved color accents only for warnings (red) and motion (blue/green).
  • Legend. Tiny key for line types, arrows, tolerances, and units.
  • Accessibility. 8–9 pt minimum type at print size; avoid color‑only distinctions—use shape and label redundancy.

File formats, resolution, and delivery etiquette

  • Working: layered PSD/AI with organized groups (Orthos, Exploded, Callouts, Tables, Legend).
  • Exchange: vector PDF for print, 4k PNG plates for wiki.
  • Resolution: design at 300 ppi for print with a 4k‑wide working canvas; export 150 ppi for shareable PDFs when file size matters.
  • Naming: WP_AR_ANCHOR_CL-AR-P03_v17_2025-10-04_Orthos.pdf (discipline prefix, class, anchor/range, pipeline step, version, date, plate type).
  • Source control: store under a predictable path; log changes in the design bible with a one‑line summary per version.

Indie vs AAA: scoping the effort

Indie. Reduce view count (side/top/front), keep exploded to sub‑assemblies only, and a single consolidated callout sheet. Focus on the few constraints that will blow your budget (attachment envelopes, reload windows, sacred silhouette planes).

AAA. Expect vendor kits: full six‑view orthos, two‑stage exploded plates (sub‑assembly + full), and discipline‑specific callout sheets (Animation/VFX/Materials). Maintain a shared template to keep hundreds of assets visually consistent; add a governance dashboard for retired parts and dependency trees.

Common failure modes and fixes

1) Floating dimensions. Dimensions reference edges that move with variants. Fix: baseline from datums and list which dimensions are sacred.

2) Ambiguous assembly. Exploded parts drift without showing fastener direction. Fix: align explosions along paths of insertion; add arrowheads and fastener icons.

3) “Wall of text” callouts. Paragraphs hide the point. Fix: one idea per callout, command voice, <20 words.

4) Animation surprises. Orthos ignore bolt/cylinder travel. Fix: include hidden dashed outlines for motion envelopes; call out min clearances.

5) Attachment collisions. Optic/suppressor space not reserved. Fix: draw attachment bounding boxes and do‑not‑occupy zones; include a worst‑case stress row.

6) Style drift at finals. Paintovers contradict mass logic established earlier. Fix: show the silhouette thumbnail and 3–4 value blocks on orthos to keep visual scaffolding honest.

Review & handoff checklist

Orthos

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Exploded Views

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Callout Sheets

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Delivery

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Closing: make the invisible visible

Great finals make invisible assumptions explicit. Orthos lock the external truth, exploded views reveal assembly reality, and callout sheets broadcast how the asset will move, attach, emit, and scale. If you author these three with discipline—and keep them aligned with your earlier silhouette bank and proportion passes—your handoff will be quiet, your builds will be fast, and your signature weapons will arrive in‑engine exactly as you intended.